Yes, they have. They're called Pocket Heretic and Pocket Hexen, and they're available for free (assuming you have your own wad files.) I just looked for the site, and it's down. I <i>just</i> deleted the original zips from my desktop this morning. I'll upload them to my server so you can download them.
Note: You need to provide the WAD files from a valid PC version of these games for them to work on your pocket PC. I did not include the wads.
http://www.aardwolf.org/data/heretic-hexen.zip (630k)